In this proposal, we seek funds to purchase a high speed, three-laser cell sorter. The sorter will be installed in the existing Flow-Cytometry core facility located at the Skirball Institute and operated by the Kaplan Comprehensive Cancer Center. It will replace a single laser FACStar Plus cell sorter that has not been operational and has been dismantled. The new sorter will have the capability to sort at speeds of about 20,000-25,000 events per second, and to sort up to four different populations, which will make possible the study of sub-populations of cells present at very low frequencies in the original samples. The combination of the three lasers will permit effective multicolor sorting and analysis using currently available fluorochromes and will also prepare NYU School of Medicine for the rapidly increasing list of new flow-cytometry applications. The features of the new sorter will allow increased flexibility in experimental design by immunologists, who have traditionally used cell sorting, and will also facilitate the growing needs of cell and developmental biologists as well as neurobiologists to sort rare populations of cells to study targets of gene activity and the developmental potential of stem cells and progenitor cells. The new cell sorter will improve the effectiveness of ongoing projects being carried out in laboratories of twelve investigators at the School of Medicine. All of these investigators, with the exception of one new junior faculty member, are supported by NIH funding. In addition, the instrument will be available to the entire NYU Medical Center community, and will enhance the research of many other groups. Its availability will enhance our ability to attract accomplished immunologists and cancer biologists in our current recruitment of senior and junior faculty. We believe that the availability of this powerful machine on our campus will elicit new exciting research projects from a variety of scientists working in the fields of cancer, immunology, and animal development.